6 W. P. Wilson. 



lection ^) . It is possible also that this fluid may sometimes take its place on 

 the surface of the nectary in the form of an excrelion. Just below the base of 

 the leaf, on the petioles of Prunus avium are two, sometimes more nectaries 

 in the form of small wart-like swellings 2] . On these nectaries as well as 

 on those of Clerodendron fragrans the production of a fluid between the 

 cuticula and the underlying cell-wallS; and the gradual raising of the former, 

 can be easily studied. Sometimes the cuticula after having been once 

 burst assunder may be renewed by the growing of a new layer, and thus 

 this process repeated. This may occur several times on the nectaries of 

 Prunus laurocerasus. On those of Acacia lophanta the diff"erent conditions 

 of the cuticula, sometimes smooth and glossy as in the youngest nectaries, 

 sometimes raised up in one or more hillocks or swellings in those nearing a 

 condition of excrelion, and sometimes the rough edges of the cuticula, in 

 cases where it has been already burst in active nectaries, can readily be 

 observed with the naked eye. 



In all those cases where the nectary possesses a cuticula it is burst in 

 this way, the nectar in no instance passing through it. In others where the 

 nectary is devoid of a cuticula the productiun of a fluid onthe surface which 

 Starts the excretion needs further study. 



Acer pseudoplatanus. 



Acer pseudoplatanus off'ers an illustration where the excretion takes 

 place through numerous stomata on the surface of the disc-shaped 

 nectary 3) . 



Upon washing and drying these nectaries two or three times I found 

 the excrelion could be as readily controlled as in the case of Fritillaria im- 

 perialis. Each Stoma opens into an open space below the guard-cells. 

 The parenchyma of the nectary is devoid of intercellular Spaces. The ex- 

 cretion takes place through the cells which bound this space, from five to 

 seven in number. 



Prunus laurocerasus. 



The nectaries on the under side of the base of the leaves of Prunus 

 laurocerasus were trealed in the same way as those of Fritillaria, and in 

 general with the same result. 



In some cases these nectaries could be made wholly inactive by three 

 washings, even wilh young leaves; with others six or seven waschings 

 were required. It is probable that in this last case a renewal of the cutic- 



1) Hanstein, Über die Organe der Harz- und Schleimabsonderung in den Laub- 

 knospen. Bot. Zelt. 1868. 



2) Reinke, Pringsheim's Jahrbücher für Botanik. Band X. 1876. p. 120. 

 / 3) Caspary, De Nectariis. 1848. p. 18. Behrens, 1. c. p. 39. 



